Brahe

King Fredrick II of Denmark built Tycho Brahe an observatory to measure
the position of planets with high accuracy. However, the telescope
had not yet been invented, so the observatory was a naked eye observatory
with oversized instruments.

Tycho Brahe (1546  1601) was born three years
after Copernicus death

A painting of Brahes naked eye observatory. The
quarter circle measurement device is drawn to the scale of the two
people in the foreground of the painting.

These instruments allowed Brahe to not only measure the positions
of planets with high accuracy, but he also calculated the measurement
error in his instruments. Ascertaining the error in scientific instruments
is expected today, but Brahe pioneered the practice.

Brahe also noted that previous measurements of the planets, as recorded
in the texts of the time, were incorrect. With his new measuring devices,
he was able to record the position of the planets with the best possible
accuracy for naked eye observations - ten times more accurately than
people had been getting until then.

Even with his high quality observations, Brahe was not able to detect
any changes in the positions of the stars over the year, which should
occur if the Earth revolves around the Sun. If he had, this would
have constituted direct proof of the Earth's motion. This
parallax effect was not detected by astronomers until the
19th century. You can see this effect by holding a finger about six
inches
from
your face and alternately closing one eye and then the other. You
should see your finger "jump" relative to background objects.

Brahe proposed a model of the solar system to explain Galileo's observation
that Venus has phases without making it necessary for Earth to be
moving. His model had all the planets (except Earth) orbiting around
the Sun, but then the Sun orbited around the Earth. This model satisfies
ALL the observations because it corresponds to reality except that
is is viewed from the point of view of someone on Earth.